xds/clusterresolver: implement gRFC A61 changes for LOGICAL_DNS clusters #8733
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Pranjali-2501
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Type: Feature
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## master #8733 +/- ##
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- Coverage 83.15% 83.11% -0.04%
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Files 414 414
Lines 32727 32730 +3
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- Hits 27214 27204 -10
+ Misses 4088 4082 -6
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This change probably needs a release note. |
internal/xds/balancer/clusterresolver/e2e_test/dns_impl_test.go
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| localityStr := xdsinternal.LocalityString(clients.Locality{}) | ||
| retEndpoint = hierarchy.SetInEndpoint(retEndpoint, []string{pName, localityStr}) | ||
| // Set the locality weight to 1. This is required because the child policy | ||
| // like wrr which relies on locality weights to distribute traffic. These |
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This is also weighted_target (which has a parent policy of wrr_locality, whose only responsibility is to build the config for weighted_target) and not wrr (which is weighted_round_robin and is a completely different policy).
| endpoints[i] = resolver.Endpoint{Addresses: []resolver.Address{a}} | ||
| endpoints[i].Attributes = a.BalancerAttributes | ||
| } | ||
| endpoints = []resolver.Endpoint{{Addresses: state.Addresses}} |
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@arjan-bal recently made a change #8812 to ensure that the DNS resolver returns endpoints. So, I think we don't need a special case here for len(endpoints) == 0. Please correct me if I'm wrong.
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Right, we don't need that special case.
| Cluster: testClusterName2, | ||
| ChildPolicy: tt.xdsLBPolicy, | ||
| } | ||
| if diff := cmp.Diff(gotConfig, wantConfig); diff != "" { |
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When using cmp.Diff, it makes more sense to pass the want as the first argument and the got as the second. And in the error string have (-want, +got). When we do this, and see an error string with some lines which have a prefix of -, we can say that those lines were expected but missing in the output. And similarly, when we see some lines with a prefix of +, we can say that those lines were not expected, but were seen in the output. See go/go-style/decisions#types-of-equality
Here and elsewhere where cmp.Diff is used in this PR.
| server2 := stubserver.StartTestService(t, nil) | ||
| defer server2.Stop() | ||
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| // Register a manual resolver with the "dns" scheme to mock DNS resolution. |
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resolve conflicts
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Fixes : #8153
This PR implements the "Changes to Logical DNS Clusters" section of gRFC A61 (IPv4/IPv6 Dual-stack Backends).
Currently,
LOGICAL_DNSclusters in the xDS cluster resolver have their Load Balancing policy hard-coded topick_first. This ensures the semantics of connecting to only one address at a time.This PR updates the
xds_cluster_resolverlogic. ThebuildClusterImplConfigForDNSfunction removes the hard-codedpick_firstpolicy restriction forLOGICAL_DNSclusters, allowing them to use the configured LB policy.Also, in the DNS update handler, all resolved addresses are now grouped into a single
resolver.Endpoint. This ensures that regardless of the configured parent LB policy, the child policy sees a single "backend" endpoint containing all addresses.RELEASE NOTES:
LOGICAL_DNSclusters now honor the LB policy configured in the cluster resource, rather than defaulting to a hardcodedpick_firstpolicy.